Circuit-interrupter

ABSTRACT

An improved circuit-interrupter is provided having an improved operating mechanism for operating the separable contacts of the circuit-interrupter unit including a novel reverse-current loop structure enabling the separable contacts to be magnetically closed under higher contact pressure during the existance of high-fault conditions, and, on the other hand, when it is desired to open the separable contacts of the improved circuitinterrupter under heavy-fault conditions with the contacts welded closed, the improved operating mechanism, including the reversecurrent loop structure, operates in the opposite manner to assist the operating mechanism to open and to separate the separable contacts of the circuit-interrupter. The improved invention additionally contemplates an improved magnetic means associated with the operating mechanism for applying additional contact closing force to hold the contacts closed under additional increased force created magnetically and instantageously at the most appropriate time with the application of the high-fault conditions. Additionally, the same magnetic means is operable, taken in conjunction with the improved operating mechanism of the instant invention, to assist the opening of welded-closed contacts during the opening operation of the circuit-interrutper by a novel relocation of the fulcrum point, which is applicable and which functions in dependence upon either the energization or the non-energization of the operating magnet structure of the operating mechanism for the improved circuit-interrupter of this invention.

i United States Patent [1 1 Hodgson 1 Nov. 18, 1975 CIRCUIT-INTERRUPTER [75] Inventor: Alfred W. Hodgson, Orchard Park,

[22] Filed: June 20, 1974 [21] Appl. No.: 481,562

Primary ExaminerI-Iarold Broome Attorney, Agent, or Firm-W. R. Crout [57] ABSTRACT An improved circuit-interrupter is provided having an improved operating mechanism for operating the separable contacts of the circuit-interrupter unit including a novel reverse-current loop structure enabling the separable contacts to be magnetically closed under higher contact pressure during the existance of highfault conditions, and, on the other hand, when it is desired to open the separable contacts of the improved circuit-interrupter under heavy-fault conditions with the contacts welded closed, the improved operating mechanism, including the reverse-current loop structure, operates in the opposite manner to assist the operating mechanism to open and to separate the separable contacts of the circuit-interrupter.

The improved invention additionally contemplates an improved magnetic means associated with the operating mechanism for applying additional contact closing force to hold the contacts closed under additional increased force created magnetically and instantageously at the most appropriate time with the application of the high-fault conditions. Additionally, the same magnetic means is operable, taken in conjunction with the improved operating mechanism of the instant invention, to assist the opening of welded-closed contacts during the opening operation of the circuit-interrutper by a novel relocation of the fulcrum point, which is applicable and which functions in dependence upon either the energization or the non-energization of the operating magnet structure of the operating mechanism for the improved circuit-interrupter of this invention.

19 Claims, 37 Drawing Figures US. Patent Nov. 18,1975 Sheet 1 of 17 FIGS US. Patent Nov. 18, 1975 Sheet 2 of 17 3,921,109

US. Patent Nov. 18, 1975 Sheet30f 17 3,921,109

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US. Patent Nov. 18, 1975 Sheet5of 17 3,921,109

Sheet 6 of 17 3,921,109

US. Patent Nov. 18, 1975 US. Patent Nov.18,1975 Sheet7of17 3,921,109

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US. Patent Nov. 18, 1975 Sheet8of 17 3,921,109

FIGJO US. Patent N0v.18, 1975 Sheet9of 17 3,921,109

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U.S. Patent Nov. 18, 1975 Sheet 10 of 17 3,921,109

FIG 14 US. Patent Nov. 18,1975 Sheet11of17 SINGLEACTING REVERSE-CURRENT LOOP PRIQR ART CURRENT FIG. l5 5 -FORCE I LOAD CONNECTION ,L\\\\\\\\\\\ I l DOUBLE-ACTING I REVERSE- CURRENT 24| LOAD CONNECTION) 203 H I F. Mwsuppom I I i I08 i DOUBLE-ACTING 24k EvsR g guRRsuT no FIG.I7 122 I 205 r'FORCE 22 OON mom-Om nm kmzwiz Sheet 12 of 17 NE mm U.S. Patent Nov. 18,1975 Sheet 13 of 17 3,921,109

M mOOJ kZMmEDQ wwmm wm mom EDP-mom GAME: I0 30F PQ FZOO US. Patent Nov. 18, 1975 Sheet 14 of 17 3,921,109

FIG. 26

FIG. 24

FIG.25

FIGZT US. Patent NOV. 18, 1975 Sheet 15 0f 17 CIRCUIT-INTERRUPTER CROSS-REFERENCES To RELATED APPLICATIONS A related patent application by A. W. Hodgson, Ser. No. 48l,423, filedJune 20, 1974 entitled ,Improved Movable Contact-Stem Operator For A Vacuum-Type Circuit-Interrupter, and assigned to the assignee of the instant patent application, discloses and claims the means for adjustment of the movable contact-stem operator for the movable contact of the circuit-interrupter disclosed herein.

BACKGROUND OF THE INVENTION Circuit-interrupters particularly of the vacuum-type are relatively new on the commercial market, and have enjoyed only limited success due to several severe shortcomings. In an effort to minimize the most serious of these shortcomings, the vacuum-interrupter have found it necessary to use contact materials which are susceptible to welding. The welding problem, however, can be minimized by the use of contact and weldbreaking forces approximately ten times those usually found in a conventional air-break contactor of comparable rating.

Vacuum-interrupters having the most desirable interrupting characteristics and longest contact life have been found to weld at currents considerably below their interrupting limit, so that the interrupting rating of a contactor using these vacuumtype circuit-interrupters is limited by the ability of the actuating or operating mechanism to overcome the welding problem, rather than by the arc-interrupting ability of the vacuum-type circuit-interrupter.

A three-pole contactor having a magnet and frame assembly proportioned to meet the design requirements of the vacuum-interrupter, and still have a reasonable mechanical life would be much too large and costly to compete with existing air break contactors which require only a fraction of the contact force. As result of this squeeze, presently available vacuumtype contactors, are a design compromise which do not completely satisfy the requirements of the vacuum interrupter, and as a result do not perform as well as existing available air-break contactors.

The very high contact forces mentioned above are required only when it is necessary to obtain the maximum monentary current rating of the vacuum-interrupter, which is in the event of a power-system fault. Since the contactor may seldom see this current condition in actual service, a contactor designed to continuously provide these high contact-closing forces would represent a rather inefficient use of space and material.

A reasonable-sized operating magnet, coupled to the interrupter shaft through a toggle mechanism, or other system of levers, could be devised to develop high contact closing forces, but the high mechanical advantage'of this mechanism would act to reduce the contact-operating speed far below the values recommended for the vacuum interrupter. The high mechanical advantage of this mechanism would, in addition, result in low or diminished contact overtravel, which, in turn, would make frequent adjustment of contact overtravel necessary.

Reverse-current loops have been employed in the past to increase the contact-closing forces under heavy fault conditions, but have had the tendency to-override the operating magnet. A reverse-current loop of this type, designed to supply the required contact-closing forces of a three-pole vacuum contactor, would exert so much force that the reverse-current loop would hold the contacts and magnet closed even after the magnet is de-energized. A weak reverse-current loop of this type would not hold the contacts closed, but would act to reduce opening speed and weld-breaking forces. which is also undesirable.

SUMMARY OF THE INVENTION In the improved vacuum-type circuit-interrupter and mechanism of the present invention, the contact closing springs, operating magnet and other structure are proportioned to provide the proper contact closing forces sufficient to insure satisfactory performance under motor starting, running, and locked-rotor conditions for the maximum sized motor with which the conta'ctor will be used. The operating mechanism for the separable contacts of the vacuum-type circuit-interrupter is such that a reverse-current loop is employed in conjunction therewith which has two oppositelydirected functions. In the closed-circuit position of the circuit-interrupter, or contactor, with the magnet energized, the fulcrum point of the reverse-current actuating arm is so located that upon a sudden increase of the current magnitude passing through the circuit-interrupter, or stated otherwise, under heavy-fault conditions existing in the controlled circuit, the magnetic forces in the reverse-current loop structure are directed to increase the contact-closing forces, thereby assisting the contact-spring pressure provided by the operating mechanism itself.

However, when it is desired, on the other hand, to open the contacts of the vacuum-type circuit-interrupter, or contactor, the de-energization of the operating magnet will be reflected through the disclosed linkage structure to change the location of the fulcrum point of the reverse-current actuating arm to thereby bring about an opposite function or effect of the reverse-current loop structure, or in other words, to redirect the forces created by the reverse-current loop structure, so that at this time the magnetic forces, generated by the reverse-current loop structure, actually assist the operating mechanism to open the separable contacts, and to break any welded condition existing at the contacts themselves.

Thus, the improved reverse-current loop structure of the present invention has two important functions. The first function is to increase the contact-closing forces, thereby assisting the contact-pressure springs in the closed-circuit position of the circuit-interrupter, when the magnet structure is energized, under the conditions of high-fault current passing through the interrupter. In this case, conceivably a remote circuit-breaker would be desired to open the circuit rather than the contactor, and the magnet would remain energized as desired. Depending on whether the operating magnet of the contactor is energized or not, depends upon whether or not the fulcrum point of the reverse-current actuating arm changes, and thereby affects the function and operation of the reverse-current loop system.

Assuming, for instance, that it is desired to open the circuit-interrupter, or contactor, the de-energization of the operating magnet structure will effect automatically a relocation of the fulcrum point of the reversecurrent actuating arm and thereby drastically change the operating function of the reverse-current loop sys- 3 tem to thereby result in an entirely oppositely-directed force, this time a force directed to open the separable contacts and thus to break any welding conditions existing thereat.

In the improved operating mechanism of the instant invention there is associated with the rotatable contactoperating arm an abutment member, such as a plate, for example, which is associated with the contact-pressure spring, and a reverse-current loop arm pivotally mounted to the contact-actuating arm has a nose portion bearing on said abutment member or plate, and operable during the de-energized condition of the magnet to act in an opening direction against said abutment plate. The fulcrum point is at the pin 107, as shown in FIG. 20, which is between the pivot shaft 132 and the reverse-current loop 221, 222. Thus, magnetic forces are brought into play to redirect the reverse-current loop effect, and to pry, in effect, the welded contacts apart, and thereby assist the opening accelerating springs of the circuit-interrupter or contactor.

In more detail, the reverse-current loop system of the present invention comprises a metallic conducting arm carrying the line current to the interrupter contacts. and pivotally mounted on the same pivot shaft location at which the rotatable contact operating arm pivotally connects to the movable contact stem of the vacuuminter-rupter. By thus being pivoted to the movable contact stem with the rotatable contact-actuating arm during heavey-fault current condition, themagnet repelling effect between the sides of the loop forces the separable contacts more firmly closed under high-fault conditions. when the magnet is energized, as is desired.

On the other hand, during the opening operation, when the operating magnet is de-energized, and the operating mechanism is stalled at the contact-touch point, due to a welded condition existing at the separable contacts; or in other words, the contacts are, in fact, welded closed, the reverse-current loop arm acts in a manner to break the contact weld by relocating the fulcrum point. of the reverse-current actuating arrn so that it now exists at the pivot point for the rotatable contact arm. The fulcrum point is at pin 107, as shown in FIG. 20.

Another very important feature of the present invention is the structure for supplying or feeding series current to the reverse-current loop arm, so that it does not oppose or tend to neutralize the magnetic action of the reverse-current loop arm. This is achieved by a special stationary current-feed circuit, which locates the current-feeding arms in roughly the same plane as the movable portion of the reverse-current loop arm, so

that, the fact, the magnetic effect, generated at the two sationary current-feed arms, is to increase and augment the magnetic effect exerted on the movable portion of the reverse-current loop-arm structure.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of motor-starter equipment including two motor starters disposed in superimposed relation together with their disconnecting-switch structures;

FIG. 2 is an enlarged view looking into the interior of a cell-structure adaptable for accommodating the improved roll-in vacuum-type circuit-interrupter structure of the instant invention, with the access doors for the low and high-voltage compartments being open;

FIG. 3 is a side-elevational view of the right side of the truck-mounted contactor, 'or interrupter assembly of the instant invention;

FIG. 4 is a side-elevational view of the lefthand side of the truck-mounted vacuum-interrupter assembly of the present invention;

FIG. 5 is a front elevational view looking at the front of the truck-mounted vacuum-type circuit-interrupter assembly of the present invention;

FIG. 6 is a vertical sectional view taken substantially along the line VIVI of FIG. 5 with the separable-contact structure closed;

FIG. 7 is an enlarged detailed view of the operating linkage and mechanism structure of FIG. 6, again the separable contacts of the vacuum-type circuit-interrupter assembly being illustrated in the closed-circuit position with the operating magnet energized;

FIG. 8 is a fragmentary vertical section view taken substantially along line VIIIVIII of FIG. 7, again the contact structure being shown in the closed-circuit position;

FIG. 9 is a view similar to that of FIG. 7, but illustrating the separable contacts of the vacuum-interrupter unit in the fully-open ciruit position with the operating magnet de-energized;

FIG. 10 is an exploded perspective view of the several parts employed in conjunction with the improved operating mechanism of the instant invention;

FIG. 11 is a somewhat diagrammatic view of the component parts of a motor-starter equipment for controlling motor installations with the disconnecting switch shown closed, and also the contactor assembly being shown in the closed-circuit position, the truckmounted elements being illustrated in their in-cell operating condition;

FIG. 12 is a top plan view ofthe reverse-current feeder circuit illustrating the structure thereof;

FIG. 13 is a side-elevational view of the reverse-current feeder structure of FIG. 12;

FIG. 14 is a front elevational view of a component part of the improved reverse-current feeder circuit of FIGS. 12 and 13;

FIG. 15 is a diagrammatic view illustrating a singleacting reverse-current loop structure with the contacts (not shown) closed, and electrical current passing through the reverse-current loop structure;

FIG. 16 illustrates diagrammatically a double-acting reverse-current loop structure utilizing some of the principles of the present invention, but illustrating a condition of a feeder connection structure, which is not commercially appropriate or desirable, the contact I structure (not shown) being illustrated in the closed circuit position, and again electrical current being illustrated as passing through the double-acting reversecurrent loop;

FIG. 17 illustrates diagrammatically the improved relocation of the feeder circuit structure of FIG. 16, in which the double-acting reverse-current loop is adversely magnetically affected by the particular feeder circuit arrangement illustrated in FIG. 17, which is, of course, undesirable;

FIG. 18 illustrates diagrammatically the closed-circuit position of the vacuum-type circuit-interrupter of the present invention, illustrating the passage of current through the reverse-current loop, illustrating the location of the pivot point or fulcrum point for the reverse-current loop arm, with the operating magnet energized, and during the existence of high-fault current 

1. A circuit-interrupter including separable contacts at least one of which is movable, a movable operating stem supporting and operating said movable contact, a movable contact-operating arm having a pivotal operating connection with said movable operating stem, means pivotally mounting said movable contact-operating arm at a second stationary pivot-point, means defining a reversecurrent movable arm also pivotally mounted on said first pivotal connection, flexible conducting strap-means having one end movable and electrically connected to said movable operating stem, said flexible conducting strap-means additionally having an actuating portion affixed to and movable with one end of the reverse-current movable arm, the other end of said flexible conducting strap means being maintained in a relatively fixed position to thereby provide a repulsion magnetic force between the legs of the reverse current-loop during heavy-fault-current conditions, operating means capable of being energized and deenergized including a contact-compression spring and an abutment member for effecting the rotation of said pivotally mounted movable contact-operating arm adjacent its free end about the second stationary pivot point, and said reverse-current movable arm bearing upon said abutment member during non-energized conditions of said operating mEans, whereby weld-breaking forces are magnetically generated about a fulcrum point at said first pivotal connection, and whereby in the energized condition of the operating means there is no contact between the abutment member and the reverse-current movable arm and additional contactclosing forces are generated at the reverse-current flexible conducting strap-means.
 2. The combination according to claim 1, wherein the operating means includes a support insulator having a threaded stud secured thereto passing through said abutment member, and a contact overtravel adjusting nut is threadedly secured to the end of said stud.
 3. The combination according to claim 1, wherein the reverse-current supply circuit includes a generally U-shaped stationary circuit having stationary legs extending on the same general level as the flexible and movable portion of the flexible conducting looped-shape strap means.
 4. The combination according to claim 1, wherein the reverse-current movable arm has a flexible strap retainer at its other end from the location of the bearing portion and maintains a fixed connection with said flexible conducting strap-means.
 5. The combination according to claim 2, wherein the pivotally-mounted movable contact operating arm comprises two leg portions having a bight portion through which said stud passes, and which bight portion serves as one end of the contact-compression spring means.
 6. The combination according to claim 1, wherein the circuit-interrputer is a vacuum-type circuit-interrupting unit.
 7. The combination according to claim 6, wherein a kickoff spring encircles the movable contact operating stem and compensates for the surrounding atmospheric pressure tending to force the separable contacts closed within the vacuum interrupter unit.
 8. The combination according to claim 4, wherein the reverse-current movable arm comprises a pair of leg portions which are secured together by said flexible strap retainer means.
 9. The combination according to claim 1, wherein the second pivotal support is provided by a generally U-shaped stationary support plate member affixed to one end of the circuit-interrupter unit.
 10. The combination according to claim 9, wherein the circuit-interrupter unit is a vacuum-interrupter unit, and the U-shaped support plate member has an aperture therethrough to accommodate the reciprocal opening and closing movements of the movable contact operating stem.
 11. The combination according to claim 1, wherein the operating means includes a laterally-extending cross-bar having two end operating arm-portions which are actuated by an operating magnet.
 12. The combination according to claim 11, wherein an operating shaft extends through a side support plate of the circuit interrupter and is actuated externally of the side support plate by the operating magnet.
 13. The combination according to claim 3, wherein the reverse-current feed-circuit comprises two substantially L-shaped leg portions dividing the current in parallel and being disposed on the same general level as the flexible movable portion of the loop-shaped flexible conducting strap-means.
 14. The combination in high-voltage motor-starter equipment of a truck-mounted assembly having a vacuum-type circuit-interrupting unit carried therewith, upper line-terminal means connected to one end of said vacuum-type interrupter unit, said one end of the vacuum interrupter unit accommodating the stationary contact thereof, load terminal means disposed at the lower end of said motor-starter equipment including a flexible loop-shaped strap-means connected to the lower-disposed movable contact stem of said vacuum-type interrupter unit, a U-shaped pivot support means secured to the lower end of said vacuum-type interrupter unit, a rotatable movable contact actuating arm having a first pivotal connection to one end of the movable contact stem, said contact arm being stationarily pivotally mounted upon a second pivot point provided by said U-shaPed pivot support means, operating means capable of being energized or being non-energized for effecting the rotation of said contact-operating arm including contact-compression springs, a relatively rigid reverse-current weld-breaking arm pivotally mounted at said first pivot point to said movable contact operating stem and having a flexible loop-shaped portion for carrying the series electrical current through said vacuum-interrupter unit, said operating means including a bearing member making at times in the non-energized state of the operating means abutment with said rigid weld-breaking reverse-current arm, said loop having a relatively stationary portion so that the magnetic repulsion forces existing between the two sides of the loop will effect additional contact-closing forces in energized condition of the operating means and an opposite opening effect during the non-energized condition of said operating means to effect weld-breaking action and a consequent opening operation of the motor-starter equipment.
 15. The combination according to claim 14, wherein the operating means includes an insulator support having an adjustable stud affixed thereto to accommodate the contact-compression spring and also a contact-overtravel adjusting nut.
 16. A circuit interrupter including separable contact means comprising at least one movable contact, a movable contact stem supporting and actuating said movable contact, a rotatable contact-actuating arm pivotally connected at a first movable pivot point to said movable contact stem and pivotally supported at a second stationary pivot point, means for effecting opening and closing motions of said contact-actuating arm (105) including an abutment portion (122), double-acting reverse-current loop-means comprising a pivotally-mounted actuating arm (136) pivotally connected to said contact stem (150) and having one end bearing on said abutment portion (122), said loop means carrying the series electrical current through said separable contact means and operable to effect a leverage action about said first pivot point during the closed-circuit position of the interrupter during the existence of heavy fault-current conditions to maintain the separable contacts closed under greater contact pressure, said double-acting reverse-current loop-means being operable at other times for a rotative leverage action about said abutment portion (122) for weld-breaking action exerted upon the separable contacts and consequent opening of the separable contact means.
 17. The combination according to claim 16, wherein the double-acting reverse-current loop means includes a rotatable prying arm pivotally mounted about said first pivot point and having attached thereto a reverse-current loop having at least one flexible movable portion.
 18. The combination according to claim 17, wherein a second portion of said reverse-current loop is stationarily mounted.
 19. The combination according to claim 18, wherein the reverse-current feeding circuit comprises a pair of stationary parallel-arranged arms in the general plane of the movable portion of the reverse-current loop-assembly. 